Systems and methods for determining field orientation of magnetic components in a ropeless elevator system

ABSTRACT

A ropeless elevator system, a propulsion system, and a method for operating a ropeless propulsion system are disclosed. The ropeless elevator system may include an elevator car, a hoistway in which the elevator car travels, and a ropeless propulsion system. The ropeless propulsion system may include electrical windings energized by a power source, the electrical windings affixed to a stationary structure, the stationary structure associated with the hoistway, and a magnet, the magnet affixed to a moving structure, the moving structure associated with the elevator car, and interaction between the electrical windings and the magnet generates a thrust force on the elevator car traveling in the hoistway. The ropeless elevator system may further include an array of Hall effect sensors, the array of Hall effect sensors determining a sensed magnetic field, the sensed magnetic field being associated with electrical currents carried by the windings and used to determine a magnetic field orientation of the electrical currents carried by the windings with respect to the magnet.

TECHNICAL FIELD OF THE DISCLOSURE

The present disclosure relates generally to elevator systems and, moreparticularly, to self-propelled elevator systems.

BACKGROUND OF THE DISCLOSURE

Self-propelled elevator systems, also referred to as ropeless elevatorsystems, are envisioned as useful in various applications, such as highrise buildings, where there is a desire for multiple elevator cars in asingle hoistway portion of the elevator system. In high rise buildings,a conventional elevator may be prohibitive due to the mass of the ropesneeded for function.

In ropeless elevator systems, a first hoistway may be designated forupward travel of the elevator cars while a second hoistway is designatedfor downward travel of the elevator cars. Further, transfer stations maybe included to move the elevator cars horizontally between the first andsecond hoistways.

To propel the elevator car about the hoistway, ropeless elevator systemsmay employ linear motors to produce necessary thrust. The linear motorsmay include current carrying coils disposed about the hoistway andmagnets disposed on one or more elevator cars. The interaction betweenthe coils and the magnet(s) generates thrust. For proper operation, therespective magnetic poles of the coils and magnets must be properlyaligned for proper field orientation. Therefore, systems and methods fordetermining field orientation of magnetic components in a ropelesselevator system are needed.

SUMMARY OF THE DISCLOSURE

In accordance with one aspect of the disclosure, a ropeless elevatorsystem is disclosed. The ropeless elevator system may include anelevator car, a hoistway in which the elevator car travels, and aropeless propulsion system. The ropeless propulsion system may includeelectrical windings energized by a power source, the electrical windingsaffixed to a stationary structure, the stationary structure associatedwith the hoistway, and a magnet, the magnet affixed to a movingstructure, the moving structure associated with the elevator car, andinteraction between the electrical windings and the magnet generates athrust force on the elevator car traveling in the hoistway. The ropelesselevator system may further include an array of Hall effect sensors, thearray of Hall effect sensors determining a sensed magnetic field, thesensed magnetic field being associated with electrical currents carriedby the windings and used to determine a magnetic field orientation ofthe electrical currents carried by the windings with respect to themagnet.

In a refinement, the magnetic field orientation of the electricalcurrents carried by the windings with respect to the magnet may be usedto determine if the electrical currents carried by the windings and themagnet are aligned for proper function of the propulsion system.

In a refinement, the magnetic field orientation of the currents carriedby the windings with respect to the magnet is used to perform faultdetection operations for the propulsion system.

In a refinement, the array of Hall effect sensors may be disposed on theelevator car.

In a further refinement, at least one member of the array of Hall effectsensors may be disposed in close proximity to a top portion of themoving structure.

In another further refinement, at least one member of the array of Halleffect sensors may be disposed in close proximity to a bottom portion ofthe moving structure.

In a refinement, the magnet may include a series of permanent magnets.

In a further refinement, the series of permanent magnets may be arrangedin a Hallbach array.

In a refinement, the windings may be arranged in a multi-phasearrangement.

In accordance with another aspect of the disclosure, a method foroperating a ropeless elevator system is disclosed. The ropeless elevatorsystem may include an elevator car and a hoistway in which the elevatorcar travels. The method may include generating a thrust force on theelevator car traveling in the hoistway, wherein the thrust force isgenerated by a ropeless propulsion system, the ropeless propulsionsystem including electrical windings energized by a power source, theelectrical windings affixed to a stationary structure, the stationarystructure associated with the hoistway and a magnet, the magnet affixedto a moving structure, the moving structure associated with the elevatorcar and interaction between the electrical windings and the magnetgenerates the thrust force. The method may further include determining asensed magnetic field, using an array of Hall effect sensors, the sensedmagnetic field associated with electrical currents carried by thewindings, and determining a magnetic field orientation of the electricalcurrents carried by the windings with respect to the magnet using thesensed magnetic field associated with the windings.

In a refinement, the method may further include determining if theelectrical currents carried by the windings and the magnet are alignedfor proper function of the propulsion system using the magnetic fieldorientation of the electrical currents carried by the windings withrespect to the magnet.

In a refinement, the method may further include performing faultdetection operations for the propulsion system using the magnetic fieldorientation of the electrical currents carried by the windings withrespect to the magnet.

In a further refinement, the method may include performing an emergencystop operation of the elevator car if a fault is detected, the faultdetermined by the fault detection operations for the propulsion system.

In a refinement, the array of Hall effect sensors may be disposed on theelevator car.

In a refinement, the magnet may include a series of permanent magnets.

In a further refinement, the series of permanent magnets may be arrangedin a Hallbach array.

In a refinement, the windings may be arranged in a multi-phasearrangement.

In a refinement, the method may further include determining, using themagnetic field orientation of the electrical currents carried by thewindings with respect to the magnet, if the magnet is properly alignedwith the windings prior to startup operations of the elevator car.

In accordance with another aspect of the disclosure, a propulsion systemfor a ropeless elevator system is disclosed. The propulsion system mayinclude electrical windings energized by a power source, the electricalwindings affixed to a stationary structure, a magnet, the magnet affixedto a moving structure and interaction between the electrical windingsand the magnet generates a thrust force, and an array of Hall effectsensors, the Hall effect sensors determining a sensed magnetic fieldbeing associated with the electrical currents carried by the windingsand used to determine a magnetic field orientation of the windings withrespect to the magnet

In a refinement, the magnet is a series of permanent magnets arranged ina Hallbach array.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a ropeless elevator system according to an exemplaryembodiment.

FIG. 2 is a top down view of an elevator car in a hoistway in anexemplary embodiment.

FIG. 3 is a top down view of a moving portion of a propulsion system inan exemplary embodiment.

FIG. 4 is a top down view of a stationary portion and a moving portionof a propulsion system in an exemplary embodiment.

FIG. 5 is a perspective view of an elevator car and a propulsion systemin an exemplary embodiment.

FIG. 6 is a schematic drawing of a propulsion system in an exemplaryembodiment.

FIG. 7 is a schematic view of configurations for magnets and windings ofa propulsion system in an exemplary embodiment.

FIG. 8 is a side view of an exemplary elevator car in a hoistway.

FIG. 9 is a schematic side view of a propulsion system associated withthe exemplary elevator car of FIG. 8.

FIG. 10 is example flow chart illustrating an embodiment of a method foroperating a ropeless elevator system.

It should be understood that the drawings are not necessarily to scaleand that the disclosed embodiments are sometimes illustrateddiagrammatically and in partial views. In certain instances, detailswhich are not necessary for an understanding of this disclosure or whichrender other details difficult to perceive may have been omitted. Itshould be understood, of course, that this disclosure is not limited tothe particular embodiments illustrated herein.

Furthermore, while the present disclosure is susceptible to variousmodifications and alternative constructions, certain illustrativeembodiments thereof will be shown and described below in detail. Theinvention is not limited to the specific embodiments disclosed, butinstead includes all modifications, alternative constructions, andequivalents thereof.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to FIG. 1, an exemplary embodiment of a ropeless elevatorsystem 20 is shown. The elevator system 20 is shown for illustrativepurposes to assist in disclosing various embodiments of the invention.As is understood by a person skilled in the art, FIG. 1 does not depictall of the components of an exemplary ropeless elevator system, nor arethe depicted features necessarily included in all ropeless elevatorsystems.

The ropeless elevator system 20 may include a first hoistway 22 in whichone or more elevator cars 24 travel upward and a second hoistway 26 inwhich the elevator cars 24 travel downward. The ropeless elevator system20 may transport elevator cars 24 from a first floor 28 to a top floor30 in the first hoistway 22. Conversely, the ropeless elevator system 20may transport elevator cars 24 from the top floor 30 to the first floor28 in the second hoistway 26. Further, the elevator cars 24 may alsostop at intermediate floors 32 to allow ingress to and egress from anelevator car 24. The intermediate floors 32 may include any floorsassociated with the first hoistway 22 and/or the second hoistway 26 inbetween the top floor 30 and the first floor 28.

Above the top floor 30, an upper transfer station 34 may be positionedacross the first and second hoistways 22, 26. The upper transfer station34 may impart horizontal motion to elevator cars 24 to move the elevatorcars 24 from the first hoistway 22 to the second hoistway 26. It isunderstood that upper transfer station 34 may be located at the topfloor 30, rather than above the top floor 30. Additionally, a lowertransfer station may be positioned across the first and second hoistways22, 26 below the first floor 28. The lower transfer station 36 mayimpart horizontal motion to the elevator cars 24 to move the elevatorcars 24 from the second hoistway 26 to the first hoistway 22. It is tobe understood that lower transfer station 36 may be located at the firstfloor 28, rather than below the first floor.

The first hoistway 22, the upper transfer station 34, the secondhoistway 26, and the lower transfer station 26 may comprise a loop 38 inwhich the cars 24 circulate to the plurality of floors 28, 30, 32 andstop to allow the ingress and egress of passengers to the floors 28, 30,32.

With reference to FIGS. 2-7, a propulsion system 50, which may beincluded in the elevator system 20, is shown. The propulsion system 50may be disposed on the elevator cars 24 in the hoistways 22, 26 and inthe transfer stations 34, 36. The propulsion system 50 may generatethrust to impart vertical motion to elevator cars 24 to propel theelevator cars 24 from one level to the next within the hoistways 22, 26and into and out of the transfer stations 34, 36. The propulsion system50 may comprise a moving part 52 mounted on each elevator car 24 and astationary part 54 mounted to a structural member 56 positioned withinthe hoistways 22, 26 and/or transfer stations 34, 36. The interaction ofthe moving part 52 and the stationary part 54 generates a thrust forceto move the elevator cars 24 in a vertical direction within thehoistways 22, 26 and transfer stations 34, 36. Such a propulsion system50 may be implemented, for example, as a linear motor.

In an example, the moving part 52 includes permanent magnets 58, whilethe stationary part 54 includes windings 60, 62 mounted on thestructural member 56. Permanent magnets 58 may be attached to a supportelement 64 of the moving part 52, with the support element 64 coupled tothe elevator car 24. Structural member 56 may be made of a ferromagneticmaterial and coupled to a wall of the first and/or second hoistways 22,26 by support brackets 66. Windings 60, 62 may be formed aboutstructural member 56. Windings 60 may comprise the stationary part ofthe propulsion system within the first hoistway 22 and windings 62 maycomprise the stationary part of the propulsion system within the secondhoistway 26. A support element 64 of the moving part 52 may bepositioned about windings 60, 62 such that the windings 60, 62 andpermanent magnets 58 are adjacent.

Windings 60 in the first hoistway 22 may be energized by a power source68 to propel one or more elevator cars 24 upward in the first hoistway22 and transfer stations 34, 36. When a voltage is applied to windings60, the interaction between windings 60 and permanent magnets 58 impartmotion to the elevator car 24. Windings 62 in the second hoistway 26operate as a regenerative brake to control descent of the elevator car24 in the second hoistway 26 and transfer stations 34, 36. Windings 62may also provide a current back to the drive unit, for example, torecharge an electrical system.

Further detailing the interaction between the permanent magnets 58 andthe windings 60, FIG. 6 illustrates an exemplary arrangement ofpermanent magnets 58 relative to the windings 60. As seen in FIGS. 2-5,the permanent magnets 58 are attached to the elevator car 24 by way ofthe moving part 52. As such, the illustrated series of permanent magnets58 may repeat for the full height of the elevator car 24.

The permanent magnets 58 may be arranged in a Hallbach array. A Hallbacharray is a specific arrangement of the permanent magnets 58 thataugments the magnetic field on one side of the permanent magnets 58while cancelling the field to near zero on the other side of thepermanent magnets 58. A Hallbach array is formed by arranging thepermanent magnets 58 in a spatially rotating pattern of magnetization.The permanent magnets 58 of FIG. 6 include arrows denoting the directionof magnetization for each individual permanent magnet 58, exemplifying aHalbach array. Such an arrangement may produce a greater magnetic fieldon a desired side while eliminating a stray magnetic field on theopposite side.

Situated between the permanent magnets 58, the windings 60, associatedwith the stationary part 54, may include groups of coils arrangedlinearly about the hoistway 22 in multi-phase arrangements. Magneticflux is created by the windings 60 when a current is applied to thewindings 60. Magnetic fields produced by the flux of the windings 60 arerepresented by the circles of FIG. 6 and the arrows at each circleindicate the direction of the flux around said circle. In the context ofthe windings 60, the magnetic poles will translate as currents when theyare changed in the coils, following the methods of vector control knownin the art.

FIG. 7 further illustrates an example propulsion system 50 having atrack 51 disposed in the hoistway 22. The track 51 may comprise aplurality of stationary parts 54. Similar to FIGS. 2-6, each stationarypart 54 includes a plurality of windings 60 mounted thereto. Eachstationary part 54 may be individually energized by the power supply 68,wherein the power from the power supply 68 may be activated/deactivatedusing a respective member of the plurality of switches 63 associatedwith the plurality of stationary parts 54.

The elevator car 24, including the moving part 52, may be disposed alongthe track 51. The moving part 52, including the permanent magnets 58,may interact with the plurality of stationary parts 54. The windings 60of a stationary part 54 may receive power from the power supply 68 whenthe moving part 52 of the elevator car 24 is aligned with the stationarypart 56 on the track 51. The controller 57 may send/receive signalsto/from the stationary parts 56 to activate members of the plurality ofstationary parts 56 where the elevator car 24 is located to propel theelevator car 24.

Turning now to FIGS. 8 and 9, the elevator car 24 is shown in thehoistway 22, wherein an array of Hall effect sensors 81 are disposed onthe elevator car 24 in close proximity to the moving part 52 and themagnets 58 therein. A Hall effect sensor 81 is a transducer thatproduces an output voltage signal in response to magnetic fields and/orvariances in magnetic fields.

A Hall effect sensor 81 may determine the magnitude and polarity of amagnetic field passing across the Hall effect sensor 81 (as shown inFIG. 9). Magnetic poles produced by the currents in the windings 60 arethe locations where the strength of the field is highest. An array ofHall effect sensors 81 can be used to determine the locations of thenorth and south poles produced by currents in the windings 60, relativeto the position of the sensors. Because the position of the Hall effectsensors 81 are known, relative to the magnets 58, output from the arrayof Hall effect sensors can be used to determine the position of themagnetic field produced by the currents carried by the windings 60,relative to the position of the magnets 58. In the present example, thedesired field orientation of the currents carried by the windings 60 maybe known and compared the magnetic field sensed by the Hall effectsensors 81 to determine if field orientation is correct. Thus, the arrayof Hall effect sensors 81 can determine a field orientation of thecurrents carried by the windings 60, relative to the magnets 58, usingthe array of Hall effect sensors 81.

The array of Hall effect sensors 81 may determine if the permanentmagnet 58 of the elevator car 24 is properly aligned with the windings60 by determining the position of the magnetic field generated by thewindings relative to the positions of the magnetic poles in thepermanent magnets 58. As seen in the arrangement of FIG. 9, segments ofthe energized windings 60 may extend beyond the array of magnets at thetop and/or bottom of the elevator car when the moving part 52 and astationary part 54 are properly aligned. Because the magnitude and angleof the current supplied to the stationary part 54 and the physicalspacing between the magnets and the Hall effect sensors 81 may beconfigured and known, the propulsion system 50 itself and/or an optionalassociated controller (e.g., the controller 67) may be able to determinethe magnetic field orientation of the magnets 58 relative to thewindings 60 based on output from the Hall effect sensors 81.

As the elevator car 24 and its associated permanent magnets 58 move, thefeedback produced by the Hall effect sensors 81 may be used to verifythat the next series of windings 60 is properly functioning when theelevator car 24 arrives in alignment with said series of windings 60,thereby performing a fault detection function. The position of the coilsegments of the windings 60 are known because the power/current levelsproduced by individual drives provided by the power source 68 are known.Using the Hall effect sensors 81, the absolute positioning of themagnets 58 relative to the windings 60 can be determined within a givenaccuracy of a number of electrical degrees based on the pole pitch ofthe windings 60.

Maintaining proper field orientation for the windings 60 relative to themagnets 58 ensures that the currents from the windings 60 and themagnetic fields of the permanent magnets 58 are oriented correctly foroptimal thrust generation and control. As the windings 60 may repeat asa series of sections about the hoistway 22, maintaining fieldorientation is useful to ensure proper section(s) of windings 60 areenergized and energized at correct levels to ensure proper function ofthe propulsion system 50. The Hall effect sensors 81 may have thefunction of determining if the section(s) of windings above or below theelevator car 24 are properly activated based on known field levels forfaultless conditions, as the magnetic field generated by the windingsshould have the same relationship to the permanent magnets 58 as theymove with the elevator car 24. For example, when the array of Halleffect sensors 81 is detecting the magnetic field of the windings 60,the Hall effect sensors 81 should always detect north and south poles inthe same location because the poles should move together. Suchmaintenance of pole positioning of the elements of the propulsion system50 is useful in controlling the propulsion system 50.

However, if the magnetic poles change when moving to another segment ofthe windings 60, then the propulsion system 50 may be experiencing aproblem. Additionally or alternatively, if no field is detected then thepropulsion system 50 may not be functioning correctly. Therefore, suchfield orientation monitoring systems are useful in fault detection ofthe propulsion system. Detecting such faults and/or propulsion problemsmay trigger a safety stop for the elevator car

FIG. 10 illustrates a flowchart 100 detailing a method of operation fora ropeless elevator system 20. At block 102, the ropeless elevatorsystem 20 receives a request to move. The request to move may come fromthe controller 57 and/or any other signals which the elevator system 20recognizes as a valid request to move. If a valid request to move isreceived, a current will be applied to the windings 60 (block 104). Thearray of Hall effect sensors 81 associated with the elevator system 20is used to sense a magnetic field associated with the electricalcurrents carried by the windings 60 (block 106). Using the sensedmagnetic field associated with the electrical currents carried by thewindings, a magnetic field orientation of the electrical currentscarried by the windings with respect to the magnet is determined (block108).

Continuing to decision 110, the method 100 may determine if theelectrical currents carried by the windings 60 and the magnet 58 areproperly aligned for functions of the propulsion system 50. Saiddecision 110 is determined using the magnetic field orientation of block108. If the windings are not properly aligned, the run of the elevatorsystem 20 is aborted. However, if windings are properly aligned, thenthe process continues.

Additionally, the magnetic field orientation determined at block 108 maybe used for a fault detection operation (decision 112). The magneticfield orientation may be used to check if pole positions align betweenthe magnet 58 and windings 60, if the proper section of windings 60 arecarrying currents, and/or any other power or alignment based discrepancyfrom a recognized normal condition. If the fault detection operationdetermines that a fault is present, then the elevator system 20 mayperform an emergency stop function (block 113).

INDUSTRIAL APPLICABILITY

From the foregoing, it can be seen that the technology disclosed hereinhas industrial applicability in a variety of settings such as, but notlimited to, systems and methods for determining field orientation ofmagnetic components in a ropeless elevator system. Using the teachingsof the present disclosure, ropeless elevator systems may be providedwith proper systems and methods for safely monitoring the fieldorientation of windings, with respect to permanent magnets, of apropulsion system. The field orientation is an important factor inproviding fault detection methods and control methods for an elevatorsystem. The systems and methods herein may also provide for verificationmeans with respect to the health of apparatus and individual apparatusfunctions associated with the propulsion system.

While the present disclosure has been in reference to systems andmethods for determining field orientation of magnetic components in aropeless elevator system, one skilled in the art will understand thatthe teachings herein can be used in other applications as well. It istherefore intended that the scope of the invention not be limited by theembodiments presented herein as the best mode for carrying out theinvention, but that the invention will include all equivalents fallingwithin the spirit and scope of the claims as well.

What is claimed is:
 1. A ropeless elevator system (20) comprising: anelevator car (24); a hoistway 22 in which the elevator car (24) travels;a ropeless propulsion system (50), the ropeless propulsion system (50)comprising: electrical windings (60) energized by a power source (68),the electrical windings (60) affixed to a stationary structure (54), thestationary structure (54) associated with the hoistway (22); and amagnet (58), the magnet (58) affixed to a moving structure (52), themoving structure (52) associated with the elevator car (24), andinteraction between the electrical windings (60) and the magnet (58)generates a thrust force on the elevator car (24) traveling in thehoistway (22); and an array of Hall effect sensors (81), the array ofHall effect sensors (81) determining a sensed magnetic field, the sensedmagnetic field being associated with electrical currents carried by thewindings (60) and used to determine a magnetic field orientation of theelectrical currents carried by the windings (60) with respect to themagnet (58).
 2. The ropeless elevator system (20) of claim 1, whereinthe magnetic field orientation of the electrical currents carried by thewindings (60) with respect to the magnet (58) is used to determine ifthe windings (60) and the magnet (58) are aligned for proper function ofthe propulsion system (50).
 3. The ropeless elevator system (20) ofclaim 1, wherein the magnetic field orientation of the electricalcurrents carried by the windings with respect to the magnet (58) is usedto perform fault detection operations for the propulsion system (50). 4.The ropeless elevator system (20) of claim 1, wherein the array of Halleffect sensors (81) are disposed on the elevator car (24).
 5. Theropeless elevator system (20) of claim 4, wherein at least one member ofthe array of Hall effect sensors (81) is disposed in close proximity toa top portion of the moving structure (52).
 6. The ropeless elevatorsystem (20) of claim 4, wherein at least one member of the array of Halleffect sensors (81) is disposed in close proximity to a bottom portionof the moving structure (52).
 7. The ropeless elevator system (20) ofclaim 1, wherein the magnet (58) comprises a series of permanentmagnets.
 8. The ropeless elevator system (20) of claim 7, wherein theseries of permanent magnets are arranged in a Hallbach array.
 9. Theropeless elevator system (20) of claim 1, wherein the windings (60) arearranged in a multi-phase arrangement.
 10. A method for operating aropeless elevator system (20), the ropeless elevator system including anelevator car (24) and a hoistway (22) in which the elevator car (24)travels, the method comprising: generating a thrust force on theelevator car (24) traveling in the hoistway (22), wherein the thrustforce is generated by a ropeless propulsion system (50), the ropelesspropulsion system (50) comprising: electrical windings (60) energized bya power source (68), the electrical windings (60) affixed to astationary structure (54), the stationary structure (54) associated withthe hoistway (22); and a magnet (58), the magnet (58) affixed to amoving structure (52), the moving structure (52) associated with theelevator car (24) and interaction between the electrical windings (60)and the magnet (58) generates the thrust force; determining a sensedmagnetic field, using an array of Hall effect sensors (81), the sensedmagnetic field associated with electrical currents carried by thewindings (60); and determining a magnetic field orientation of theelectrical currents carried by the windings (60) with respect to themagnet (58) using the sensed magnetic field associated with the windings(60).
 11. The method of claim 10, further comprising determining if theelectrical currents carried by the windings (60) and the magnet (58) arealigned for proper function of the propulsion system (50) using themagnetic field orientation of the electrical currents carried by thewindings (60) with respect to the magnet (58).
 12. The method of claim10, further comprising performing fault detection operations for thepropulsion system (50) using the magnetic field orientation of theelectrical currents carried by the windings (60) with respect to themagnet (58).
 13. The method of claim 12, further comprising performingan emergency stop operation of the elevator car (24) if a fault isdetected, the fault determined by the fault detection operations for thepropulsion system (50).
 14. The method of claim 10, wherein the array ofHall effect sensors (81) are disposed on the elevator car (24).
 15. Themethod of claim 10, wherein the magnet (58) comprises a series ofpermanent magnets.
 16. The method of claim 15, wherein the series ofpermanent magnets are arranged in a Hallbach array.
 17. The method ofclaim 10, wherein the windings (60) are arranged in a multi-phasearrangement.
 18. The method of claim 10, further comprising determining,using the magnetic field orientation of the windings (60) with respectto the magnet (58), if the magnet (58) is properly aligned with thewindings (60) prior to startup operations of the elevator car (24). 19.A propulsion system (50) for a ropeless elevator system (10), theropeless propulsion system (50) comprising: electrical windings (60)energized by a power source (68), the electrical windings (60) affixedto a stationary structure (54); a magnet (58), the magnet (58) affixedto a moving structure (52), and interaction between the electricalwindings (60) and the magnet (58) generates a thrust force; and an arrayof Hall effect sensors (81), the array of Hall effect sensors (81)determining a sensed magnetic field, the sensed magnetic field beingassociated with electrical currents carried by the windings (60) andused to determine a magnetic field orientation of the electricalcurrents carried by the windings (60) with respect to the magnet
 58. 20.The propulsion system of claim 19, wherein the magnet is a series ofpermanent magnets arranged in a Hallbach array.